Process of activating carbon



Aug 119 1924;

J. C. W OODRUFF ET AL.

PROCESS OF ACTIVATING CARBON Filed May 5, 1919 Hoa /14 e1 Patented Aug. 19, 1924.

STATES 1,505,517 PATENT OFFICE.

JOHN C. WOODRUFF AND THORNE L. WHEELER-,0]? NEW YORK, N. Y.

PROCESS OF AGTIVATING CARBON.

Application filed May '5, 1919. Serial No. 294,799. 1

To all whom it may concern:

Be it known that we, JOHN C. VVOODRUFF and THORNE L. WHEELER, citizens of the United States, and residing at New York city and New York city, respectively, have invented certain new and useful Improvements in Processes of Activating Carbon, of which the followingis a specification.

This invention relates to the manufacture of absorbent carbon such as charcoal and has special reference to a process of rendering the carbon highly active as an absorbent.

Heretofore, charcoal has been activated by means of steam in vertical tube furnaces called Dorsite treaters. This type of furnace consists of a nichrome tube symmetrically set in a vertical position and surrounded by a cylindrical combustion chamber heated to about 1100 C. by gas ,burners. On the inside of the above mentioned tube, there is concentrically located a nichrome steam pipe having part of its length perforated, and

covered with nichrome wire cloth of ratherfine mesh which is smaller than the particles of. the material treated. The gaseous products of the reaction are drawn off through exhaust ports by means of a vacuum pump. Granular charcoal is introduced through a hopper valve feeding device at the top. The space surrounding the steam jet is kept full of carbon and as a portion is discharged from the bottom of the tube, thus lowering the level of material in the tube, the level is replenished through the feed valve at the top of the furnace. Thus a continuous gravity passage of the charcoal through the tube is maintained, unless interfered with by gas pockets, and the charcoal is activated by the superheated steam admitted through the steam et.

The highest quality of absorbent charcoal is obtained only by running the material at a very slow rate or by re-running it several times through this type of furnace. This process requlres a large amount of time and fuel.

Difficulty is experienced in feeding due to the formation of gas 'ockets which hold the charcoal from sliding after ma terial is discharged from the bottom. The exhaust lines constantly give troubleby becoming plugged with charcoal. 7

One of the objects of our invention is to provide a process which is more efiieient and simpler to operate than the rior processes; also cheaper and which may e condpctedin a continuous manner and which 'w1ll overand rotates with the pipes (20) and come the disadvantages heretofore described in the prior processes.

Itcference is to be had to the accompanying drawings in which: i

Fig. 1 is a side elevation of the apparatus used for carrying out our process.

Fig.2 is an end elevation.

The apparatus is provided with a large tube (1)", preferably of nichrome, havin carrying rollers (2) which rest upon radia rollers (3) supported by the bearings (4),

ing (5) The bearings rest on a steel frame (6) which is supported on the concrete piers the thrust being taken up by the thrust bear- 7 (7 and foundation members (8). The tubel is rotated through any suitable driving connectlon with a bevel gear attached to either of the rollers (2). It should be understood that any suitable supporting means may be used in place of that herein described without departing from the spirit and scope of this invention. I

The charcoal is introduced into the tube.

(1) through the double seal hopper (9), provided With Valves (10) and (11), and is.dis-

charged through another double seal hopper 21 which are also supported by the plates (15 supported in the end plates (15) and (16) and (16). The hoppers (9) and gether with their attached valves (10), (11), (13) and (14:) also rotate.- The tube (1) ro tates slowly, for example two revolut ons per minute. When the hopper is in upri ht position as shown in Fig.1, the operator as.

suflicient time while the hopper is rotating to close the valve (11) open the valve (10), insert a charge of hopper (9), reclose the valve (10) and reopen the valve (11) before the hop er has uring traveled to a horizontal position.

raw material into the the next revolution, when the ho per (9) is again in upright position the va ve (11 is open and the charge from the ho per (9) is delivered into the pipe (20) an thus into the tube (1). On thenext revolution, the

valve (11) is closed, valve opened and another charge of raw material introduced into the hopper In dlschargmg the activated 'material from the apparatus, with the hopper (12) in the position shown in Fig. 1, valve (13) is opened and valve (14) closed. The material Wlll flow from v the tube (1) through the pipe (21) into the hopper 12) when the latter is in the down position. As the hopper revolves, the valve (13) is closed before the hopper reaches the horizontal position. On the next down movement of the hopper, the valve (14:) is opened while the valve (13) is closed and the contents of the hopper (12) discharges through the valve (14) as the hopper approaches its low position. The tube (19) 1S perforated and. serves to supply steam to the interior of tube (1). This tube (19) has an enlarged portion (22) at one end, whichis separated from the main portion of the pipe (19). Steam enters the tube (19) at (23) through a stufling box and passes through the perforations (24:) into the pipe 1) containing the charcoal to be activated. The portion (22) is closed at the point where it joins the main portion of the pipe (19); this portion (22) being also provided with perforations (25) which serve to draw off the products ofreaction from the tube (1).

The furnace is slightly inclined, so that charcoal fed in at the upper end, from the hopper (9), moves slowlv down the tube (1) as 'it slowly rotates, and is activated by superheated steam from the steam jet.

The tube (1) is surrounded by a combustion chamber (26) which is stationary and heat is supplied to this combustion chamber from the burners (27), and the products of combustion pass out through the fines,- (28). In order to ascertain the temperature within the combustion chamber, pyrometers (29) are provided.

Although usually we prefer to introduce steam through a pipe such as (19) other means may be effectively substituted therefor. Steam may bra-introduced at one end of the pipe 1) through any suitable means and the products of combustion withdrawn from the other end. This type we have termed open end jet. The pipe (1) may also be provided with spurs or flights (30) which are either fastened to or cast in the pipe (1) and serve to agitate the material within the tube 1) by lifting and dropping the material as the tube (1) rotates. V The material thus drops through the atmosphere of steam or other'oxidizing gas, such as air or CO used for activation. Also, the pipe (19) need not'necessarily be circular in cross section, but any other convenient form may be used, and the use of fake like tubing instead of the straight tube (19) is also contemplated. Either of the methods herein descrlbed for introducing the activating gas or fluid may be used singly or in combination with one or more of the other methods.

We have found that the most desirable results are obtained when the charcoal is heated to a temperature between 700 and 1100 (1, and this condition maybe obtained in tube (1) by heating the combustion chamber to a temperature of about 1100 C. This will superheat the steam within tube (1). Of course, it should be understood that the steam entering tube (1) from tube (19) may or may not be superheated outside of the furnace as desired.

This process not only activates the charcoal in a much shorter period of time than the old processes, but the product is of an. exceedingly high absorbing power, and the quality of the product is very much more uniform than that produced by the old processes. The successful accomplishment of the results described depends upon the employment of an oxidizing agent, preferably endothermic, such as steam, and the application of the oxidizing agent in a manner which insures repeated contact of all of the carbon therewith during its treatment. The acceleration of the reaction is accomplished through the combined agitation of the carbon and thorough distribution of the steam in the reaction chamber, which permits rapid passage ofthe carbon. While air and carbon dioxide have been employed for revivifying bone black and the like, they do not possess the advantages of the steam. The reaction employing the latter agent is endothermic so that oxidation is readily controlled and waste of active material is thereby prevented. Steam has been heretofore suggested as an oxidizing agent in the treatment of carbon, but it has never, so far as we are aware, been employed in the manner described to insure thorough distribution thereof through a mass of material under treatment for the purposes of our invention.

The uniform and very active product may be used for a variety of purposes to which it is adapted and being produced economically forms a desirable article of commerce.

The present invention is not limited to the specific details set forth in'the foregoing examples which should be construed as illustrative and not by way of limitation, and. in view of the numerous modifications which may be effected therein without departing from the spirit and scope of this invention, it is desired that only such limitations be imposed as are indicated in the appended claims.

We claim as our invention:

1. A process of increasing the adsorptive power of carbon by oxidation, which comprises conveying the carbon through an elongated heated reaction zone, distributing an active oxidizing agent throughout the reaction zone so that all of the carbon therein is simultaneously subjected to the action of the oxidizing-agent before the latter is materially contaminatedby the end products of the reaction, the carbon being maintained during the reaction at a temperature sufficiently high to ensure rapid activation, by the external application of heated combustion products.

2. A process of increasing the adsorptive power of carbon by oxidation, which comprises agitating the carbon in an elongated heated reaction zone, distributing an active oxidizing agent throughout the reaction zone so that all of the carbon therein is simultaneously subjected to the action of the oxidizing agent before the latter is materially contaminated by the end products of the reaction, the carbon being maintained during the reaction at a temperature suiiiciently' high to ensure rapid activation, by the external application of heated combustion products.

3'. A process of increasing the adsorptive power of carbon by oxidation, which comprises agitating the carbon in an elongated heated reaction zone, distributing steam throughout the reaction zone so that all of the carbon therein is simultaneously subjected to' the action of the steam before the latter is materially contaminated by the end products of the reaction, the carbon being maintained during the reaction at a temperature 'sufliciently high to ensure rapid activation by the external application of heated combustion products.

4. A process of treating carbon by endothermic oxidation which comprises, subjecting the carbon to continued agitation while conveying it through a reaction zone, supplying steam to said zone during agitaheating chamber, supplying steam to said zone during agitation of the carbon so that the steam is intimately mingled with the carbon and maintaining a temperature rangingfrom 700 C. to 1100 C. within the chamber and during the oxidation by the external application of heated combustion products. 7

6. A process of treating carbon by endothermic oxidation which comprises, sub- "jecting the carbon to continued agitation while conveying it through a reaction zone having walls of oxidation resistant material, supplying steam to said zone during agitation of the carbon so that the steam is intimately mingled with the carbon and heating said zone by transfer of heat through said walls to a temperature sufficiently high to insure a rapid activation of the carbon.

JOHN C. 'WOODRUFF. THORNE L. WHEELER. 

